基于旋转压实的水泥稳定再生集料设计方法

A Design Method of Cement Stabilized Recycled Aggregate Based on Rotary Compaction

废旧水泥混凝土再生集料具有吸水率较高的特点,将其用于路面半刚性基层时传统的击实设计方法得到的水泥稳定再生集料含水量偏高,半刚性材料更加容易发生干缩开裂。为了解决这一问题,提出采用旋转压实成型方法设计水泥稳定再生集料,减小再生混合料的干缩变形,形成适用于再生集料的水泥稳定再生材料设计方法。通过室内试验对比水泥稳定再生集料在传统成型方法下与旋转压实成型方法下的配合比设计结果,试验结果表明:采用旋转压实成型法设计得到的水泥稳定再生集料的最佳含水量较传统方法得到的小;旋转压实80次的干密度指标对应于传统击实法的设计结果,但旋转压实试件的强度高于静压法试件;当水泥用量超过7%时,材料的强度主要受水泥控制,成型方法对强度影响较小;存在一个使水泥稳定再生集料的最佳含水量与最大干密度达到稳定的压实次数,可通过设置合理的压实次数,以最大干密度与抗压强度稳定状态为设计目的确定配合比。研究提出的旋转压实设计方法更适用于水泥稳定再生集料的配合比设计,可用于指导水泥稳定再生集料基层或垫层的材料设计。

The recycled aggregate of waste cement concrete has the characteristics of higher water absorption.The water content of cement stabilized recycled aggregate is higher when using the traditional compaction design method for the semi-rigid pavement base,leading to more prone to shrinkage cracking for semi-rigid materials. In order to solve this problem,the rotary compaction method is proposed to design the cement stabilized recycled aggregate to reduce the shrinkage deformation of the recycled mixture and to form the design method of cement stabilized recycled material suitable for recycled aggregate. The mix design results of cement stabilized recycled aggregate under the traditional molding method and the rotary compaction method are compared by laboratory test. The experimental result shows that（ 1） the optimum water content of the cement stabilized recycled aggregate obtained by rotary compaction method is smaller than that obtained by traditional method;（ 2） the dry density index of 80 rotary compactions complies with the design result of traditional method,while the strength of the rotary compaction specimen is higher than that of the hydrostatic specimen;（ 3） when the cement content exceeds 7%,the strength of the material is mainly controlled by cement,and the forming method has little effect on the strength;（ 4） there is a stable repetition times of compaction for the optimum water content and maximum dry density of the cement stabilized aggregate toobtain a steady state,the stability states of maximum dry density and the compressive strength can be used as the objective to design the mix proportion by setting the reasonable repetition times of compaction. The proposed rotary compaction design method is more suitable for the design of the mix proportion of cement stable recycled aggregate,which can be used to guide the design of materials of cement stabilized recycled aggregate base or cushion.